The clinical pharmacology of the sulfonamides is generally characterized by the following. A single 2.0 gram dose of sulfisoxazole results in a mean time of peak plasma concentration of 2.5 hours. About 97% of the original dose is excreted in the urine within 48 hours. The mean elimination half life is 5.8 hours, ranging from 4.6 to 7.8 hours. These characteristics are typical of the other "sulfa"-type drugs such as sulfamethizole, sulfamethoxazole and sulfasalazine.
In the case of quinine, its salts, and the other cinchona alkaloids, peak plasma concentrations occur within 1 to 3 hours after a single oral dose of 260 mg in the form of the sulfate. The half-life is 4 to 5 hours. After termination of quinine therapy, the plasma level falls rapidly and is barely detectable after 24 hours.
The present invention relates to the treatment of diseases caused by bacterial and viral infections such as malaria, dysentery and the like.
The present day treatment of such diseases requires the repeated administration of the appropriate drug to the patient, for example, quinine in the case of malaria, and sulfathiazole in the case of dysentery. The need for repeated administration is due to the fact that the drug is rapidly eliminated from the circulating plasma and the body, as noted above. Rapid elimination of the drug significantly increases the complexity of treatment and prolongs it. Repeated administration is not always effective, and the process of the repeated administration makes more complicated the organization of the drug and works negatively on the psychology of the patient.
Increasing the residence time of a drug within the patient prolongs the effect of the drug, provides more uniform plasma levels, and reduces the number and frequency of side effects.
The present invention provides for the prolongation of the efficacy of the drug in mammals including humans by prolonging the plasma residence time.
By the practice of this invention, a single administration of a drug such as quinine dihydrochloride and sulfathiazole persists in the blood plasma up to 28-30 days. It is believed that the present invention represents a major advance in pharmacology and that it will be widely adapted by those skilled in the art.